Rafter tool



R. E. DAY

RAFTER TOOL May 8, 1956 Filed Nov. 2. 1954 [FIG 2 INVENTOR. ROBERT E. DAY

Wm w ll United States Patent RAFTER TOOL Robert E. Day, Worcester, Mass. Application November 2, 1954, Serial N 0. 466,288

Claims. (Cl. 33-93) This invention relates to tools for use in building construction and more particularly to a novel tool for laying out rafters and the like by determining their correct angle and length.

Heretofore, it has been a diflicult problem in the construction of wooden frame buildings to lay out and prepare cut roof rafters to the proper angle and length. The main reason for this ditficulty arises from the fact that although the common practice is to measure the angle and distance between the top of the plate member at the edge of the building and the top of the ridge member at the peak of the building in order to lay out a rafter, such angle and length are not correct, since the rafter normally rests on the plate member and extends above it for a distance determined both by the vertical dimension of the rafter and by the bottom cut in the lower edge of the rafter to receive the plate member. Thus, with such method used to lay out a rafter, the resulting cuts will be in error both as to angle and distance and the rafter will not fit properly between the plate member and'the ridge.

Accordingly, as an object of the present invention, I have provided a novel tool for determining rafter angle and length by the use of which rafters may be laid out and pre-cut with heretofore unknown precision as to both rafter angle and length.

It is a particular feature of the invention that my novel tool may be quickly and easily adjusted so that it may be used to lay out rafters of a number of vertical dimen- 510118.

For the purpose of explaining a preferred embodiment of the tool of my invention, reference is now made to the following specification, together with the accompanying drawings wherein:

Figure 1 is an isometric view of the tool of my invention;

Figure 2 is a view of the use of the tool of Figure 1 in measuring a desired rafter angle and length;

Figure 3 is a view of the use of the tool of Figure l in laying out a rafter to be pre-cut; and

Figure 4 is a detail view of a modification of the tool of Figure 1.

Referring to the drawings, the rafter angle and length finding tool of my invention comprises a main body member which is in essence a carpenters square, having a horizontal arm 12 and a vertical arm 14 rigidly mounted thereon. The inner working surfaces of the square, that is the lower edge 11 of the horizontal arm and the edge 13 of the vertical arm intersecting it are preferably transversely extended as shown to provide a bearing surface for the tool and to enable its ready clamping to the plate member of a building. The vertical arm 14 extends upwardly as well as downwardly from the horizontal arm lower edge 11 and has an outer edge 15 parallel to the inner edge 13 of its downwardly extending portion for the entire vertical extent of the vertical arm 14.

The upper arm portion is provided with a plurality of Patented May 8, 1956 vertically spaced mounting holes 16, 17 and 18, an alining arm 20 preferably having a transversely extended lower alining edge 21 being releasably mounted in a selected one of said holes by means of a machine screw 22 and wing nut 24, said screw passing through one of said holes, herein shown as 16, to permit either pivotal movement of said arm relativev to said upper arm portion or to permit said arm to be clamped against said upper arm portion all as hereinafter more fully explained. The holes 16, 17 and 18 are positioned at spaced distances from the horizontal arm lower edge 11 so that the tool may be adjusted to accommodate rafters of various sizes. Although many rafter sizes could be accommodated by using a larger number of holes, I have found that holes 16, 17 and 18 are preferably positioned at suitable distances to measure and lay out rafters of four, six and eight inch vertical dimensions respectively.

In order to permit the lower alining edge 21 of arm 20 to move pivotally while maintaining its intersection with the continuation of the line of the inner edge 13 of the lower arm portion (the inside plumb line) at a constant distance along said line from the horizontal arm lower edge 11, the arm may be pivoted at its alining edge and the holes 16, 17 and 18 positioned along said line at the predetermined distances from the horizontal arm lower edge corresponding to the size of the rafters to be laid out and pre-cut and the depth of the rafter lower cut for receiving the plate, such lower cut being of a conventional size for any given rafter size. It will be appreciated that the upper arm portion extends sufficiently along the horizontal arm to include such line.

However, although the arm may be mounted on its working edge by means hereinafter described in connection with Figure 4, I have found that a simpler construction as shown in Figures 1 through 3 may be provided by positioning the alining arm pivot point along a line extending from the intersection of the alining arm alining edge 21 and the inside plumb line 13 and perpendicular to said alining arm edge, the alining arm 20 being set to an intermediate rafter angle which as a matter of practice may be about 30. With such arrangement, the error caused by pivoting the alining arm 20 at a distance from its alining edge 21 of about one half inch is so small as to be negligible from a practical standpoint.

However, if the highest accuracy be desired, as shown in Figure 4 a supplemental member 26 may be interposed between the alining arm 20 and the vertical arm portion 14 of the square, said member being mounted on the alining arm 20 by any suitable means such as a screw 28 and having its axial screw 22 at the alining edge of the arm 20.

To avoid the use of an alining arm of inconvenient length, I have further provided said arm with a flexible extension member such as a steel rule 30 releasably mounted at one end of alining arm 20 by means of a hook 34 passing through a hole 32 in said arm. It is important, however, that the flexible member mounting hole 32 be located substantially on a line parallel to the alining arm edge and passing through the pivot point of the arm so that said arm will be alined with the steel rule when the latter is pulled taut.

In operation, as best shown in Figure 2 the alining arm 20 is first adjusted to one of its mounting holes 16, 17 or 18 in conformance with the size of rafter to be laid out and pre-cut. The tool is then positioned on the plate member 40 of a building with the inner edges of the square there against and is preferably clamped by any suitable means (not shown). With the alining arm clamping wing nut 24 released sufficiently to permit pivotal movement of said arm, the flexible rule 30 is pulled taut to the peak of the building ridge member 42 and the alining arm 20 is then clamped in position to define the rafter angle, the measurement of the distance to the ridge member alsobeing noted while the ruleis taut:

Turning now to Figure 3, the tool may then be removed from the plate member and positioned, on a suitable board 44 to be laid out and prec ut as a rafter. Although. this'may be-d'one ina number of ways, the tool for example maybe positioned on the board; a sufficient distance from theends thereoftoaccommodate rafter length from the plate fotheridge and to the end of'tlie' desired overhang; and theboard is then marked along the' inner edges of the square to define the rafter bottom cut for accommodating the plate member. The noted measurement is next marked on the board, and: the tool moved. to position the outer vertical edge at such mark to define, the ridge cut: The overhang cut is similarlydefined by measuring inthe other direction. from the inside plumb line of the plate member cutand repositioning the tool sothat the outside vertical edge defines the overhangcut.

The board then beingmarked as. above noted to designated the needed cuts, may then be cut' to provide without further measurements, a completed rafter ofaccurate dimensions;

It will be apparent to those skilled in the art that various modifications may be made. within the spirit of my" invention and the scope of the appended claims.

I claim:

1'. A tool for determiningrafter angle and length comprising a square having a horizontal arm with a lower edge and a vertical arm rigidly mounted on said horizontal arm and having a portion extending downwardly therefrom with a vertical inner edge and a vertical outer edge parallel thereto, and a portion extending upwardly therefrom with a vertical outer edge'continuous with said outer edge of said lower portion and having therein a line continuous with said inner edge of said lower portion, analining arm having a lower alining edge, said arm being mounted on said vertical arm portion for pivotal movement and releasable clamping means for mounting said alining arm for pivotal movement on said vertical arm portion in one of a plurality of predetermined positions spaced from said' horizontal arm lower edge.

2. A tool as claimed in claim 1 wherein each of said" predetermined positions are substantially on the alining edge" and on the line continuous with the inner edge of the lower vertical portion of the vertical arm.

3. A tool as claimed in claim 1 wherein each of said predetermined positions are substantially on a line perpendicular to said alining edge at an intermediate angular position of said alining arm.

4. A tool as claimed in' claim 3 wherein said intermediate angular position is about 30 degrees from said horizontal arm lower edge.

5. A tool for determining rafter angle and length comprising a. square having a. horizontal arm with a lower transversely extending edge and a vertical arm rigidly mounted on said. horizontal arm. and having a portion extending downwardly therefrom with a vertical inner edge and a vertical outer edge parallel thereto and a portion extending upwardly therefrom with a vertical outen edge continuous with said outer edge of saidlower portion and having therein a. line continuous. with said inner edge of said lower portion, an alining. arm, having, a lower alining edge, said arm being mounted on. said vertical arm portion for pivotal movement and having a flexible extension mounted at one end thereof on a. line parallel to said alining edge and passing through. sai'dlpivotpoint and releasable clamping means for mounting said alining arm on said vertical arm portion in one of a plurality of predetermined positions spaced from said horizontal arm lower edge, said means including a plurality of'hol'es in said vertical arm portion spaced. at predetermined distances from said horizontal edge and screw threaded means on said alining arm passing through one of said holes for releasably mounting said arm for pivotalmovement and for clamping said arm to said verticalarm portion.

References Cited in the file of this patent UNITED STATES PATENTS 496,714 Allred May l', 1893 1,290,977 Greene Jan. 14, 1919 FOREIGN PATENTS 197,045 Germany Apr. 4, 1908 

